Inhaled farm dust alters gut bacteria and weakens intestinal barrier in mice

Inhaling agricultural dust may pose significant risks to gut health for workers in animal agriculture, a University of California, Riverside, study has found.

Led by Declan McCole, a professor of biomedical sciences in the UCR School of Medicine, the study expands on prior findings that hog farm dust causes airway inflammation. The researchers now report in the Journal of Applied Toxicology that inhaling this dust also alters the gut microbiome and impairs intestinal function, including increased “leaky gut” or intestinal permeability. Leaky gut is associated with a range of chronic diseases, including inflammatory bowel disease, celiac disease, and type 1 diabetes.

“Exposure to swine farm dust, which contains high levels of bacteria and endotoxins, caused both airway inflammation and increased passage of gut bacterial products into the bloodstream in our mouse models,” said Meli’sa Crawford, a former postdoctoral researcher in McCole’s lab and the paper’s first author. “But what’s especially striking is the impact we observed on the gut microbiome and metabolism.”

The researchers exposed mice intranasally to hog dust extract for three weeks. The mice showed a significant drop in beneficial bacterial species, including Akkermansia muciniphila, Clostridium sp. ASF356, and Lachnospiraceae bacterium.

The research team also found decreased levels of critical compounds in the gut of the mice, such as riboflavin, nicotinic acid, inosine, and leucine—key players in energy metabolism, immune regulation, and gut barrier maintenance.

“While most research has focused on the respiratory effects of farm dust, our findings clearly show that inhaled pollutants can have systemic consequences,” McCole said. “This research underscores the importance of considering the gut–lung axis when assessing the health risks of bioaerosol exposure in agriculture.”

The study builds on growing evidence that pollution from concentrated animal feeding operations can impact multiple organ systems.

“Agricultural dust is rich in fine particulate matter and resistant bacteria, presenting a complex threat to farmworkers’ health,” McCole said. “Our earlier work showed that inhaled hog dust extract leads to neutrophilic lung inflammation. We now show the link to intestinal barrier dysfunction and microbial imbalance, highlighting the need for improved workplace protections for agricultural workers to mitigate long-term health consequences.”

The study was supported by grants from the National Institutes of Health; University of California, Davis-Western Center for Agricultural Health and Safety; and University of California Presidential Postdoctoral Fellowship Program. Crawford is now an assistant professor in the Department of Animal Sciences at Rutgers University in New Jersey.

The title of the research paper is “Respiratory Exposure to Agriculture Dust Extract Alters Gut Commensal Species and Key Metabolites in Mice.”

Inhaling agricultural dust may pose significant risks to gut health for workers in animal agriculture, a University of California, Riverside, study has found.

Led by Declan McCole, a professor of biomedical sciences in the UCR School of Medicine, the study expands on prior findings that hog farm dust causes airway inflammation. The researchers now report in the Journal of Applied Toxicology that inhaling this dust also alters the gut microbiome and impairs intestinal function, including increased “leaky gut” or intestinal permeability. Leaky gut is associated with a range of chronic diseases, including inflammatory bowel disease, celiac disease, and type 1 diabetes.

“Exposure to swine farm dust, which contains high levels of bacteria and endotoxins, caused both airway inflammation and increased passage of gut bacterial products into the bloodstream in our mouse models,” said Meli’sa Crawford, a former postdoctoral researcher in McCole’s lab and the paper’s first author. “But what’s especially striking is the impact we observed on the gut microbiome and metabolism.”

The researchers exposed mice intranasally to hog dust extract for three weeks. The mice showed a significant drop in beneficial bacterial species, including Akkermansia muciniphila, Clostridium sp. ASF356, and Lachnospiraceae bacterium.

The research team also found decreased levels of critical compounds in the gut of the mice, such as riboflavin, nicotinic acid, inosine, and leucine—key players in energy metabolism, immune regulation, and gut barrier maintenance.

“While most research has focused on the respiratory effects of farm dust, our findings clearly show that inhaled pollutants can have systemic consequences,” McCole said. “This research underscores the importance of considering the gut–lung axis when assessing the health risks of bioaerosol exposure in agriculture.”

The study builds on growing evidence that pollution from concentrated animal feeding operations can impact multiple organ systems.

“Agricultural dust is rich in fine particulate matter and resistant bacteria, presenting a complex threat to farmworkers’ health,” McCole said. “Our earlier work showed that inhaled hog dust extract leads to neutrophilic lung inflammation. We now show the link to intestinal barrier dysfunction and microbial imbalance, highlighting the need for improved workplace protections for agricultural workers to mitigate long-term health consequences.”

The study was supported by grants from the National Institutes of Health; University of California, Davis-Western Center for Agricultural Health and Safety; and University of California Presidential Postdoctoral Fellowship Program. Crawford is now an assistant professor in the Department of Animal Sciences at Rutgers University in New Jersey.

The title of the research paper is “Respiratory Exposure to Agriculture Dust Extract Alters Gut Commensal Species and Key Metabolites in Mice.”